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Tankless Water Heaters

Rinnai Tankless Solutions Give You the Power to Live Better

An endless supply of hot water, whenever you need it—even for multiple tasks at the same time. Tankless Water Heaters revolutionize comfort, energy efficiency and convenience.

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Flexible Tankless Venting Options

A First in Both Concentric and PVC/CPVC Venting for Condensing Tankless Water Heaters On One Model

The new RUR and RUC models of the Rinnai Ultra Series Tankless Water Heaters are the only tankless water heaters to offer Concentric Polypropylene or dual-pipe PVC/CPVC venting options on the same model. The dual venting configuration on the top allows for maximum flexibility for installers and dealers — one Concentric vent or two PVC/CPVC pipes can be used for venting

As the #1 selling brand of tankless water heaters in the U.S. and Canada, we still favor Concentric Polypropylene for its superior joint fit, no cure time, quick installation and reduced wall or roof penetrations, but as leaders in the industry, we understand that PVC/CPVC can sometimes be more readily available or preferred in some installations.

Rinnai is the only tankless water heater manufacturer to offer both Concentric and dual-pipe PVC/CPVC on the same model, providing more venting options right out of the box — saving time, money and offering the best flexibility for faster installations in homes and businesses — from one project to the next.

Dual pipe venting options available on RUR and RUC Tankless Water Heaters include:

  • 3" or 4" PVC/CPVC*
  • 3" Centrotherm InnoFlue Vent System (ULC-S636 listed)*
  • IPEX Concentric and Low Profile Termination Kit*
  • Snorkel and Tee Terminations*


For concentric venting, installers simply remove and discard the exhaust adapter ring.

Concentric PP 65 Feet**
(19.8 m)
41 Feet
(12.5 m)
41 Feet
(12.5 m)
Twin Pipe PP (Centrotherm) 41 Feet**
(12.5 m)
41 Feet
(12.5 m)
41 Feet
(12.5 m)

For PVC/CPVC configurations, the intake cap is removed and discarded. With this option, installers can use three- or four-inch PVC/CPVC pipe for the intake and exhaust.

3” Dual Pipe PVC/CPVC (76.2 m) 65 Feet** (19.8 m) 41 Feet (12.5 m) 41 Feet (12.5 m)
4” Dual Pipe PVC/CPVC 10.16 m) 100 Feet** (30.5 m) 65 Feet (19.8 m) 100 Feet (30.5 m)

* Reference Rinnai Tankless Water Heater Installation and Operation Manual for further information.

** Maximum equivalent vent lengths are specific to the fuel type of the RUC and RUR tankless water heater. Use of elbows in installation will reduce the maximum vent length. It is imperative when performing equivalent vent length calculations, that you refer to the Installation Manual and any applicable technical bulletins.

Rinnai Makes Your 1/2” Gas Line an Option, Not an Obstacle.

If your tankless water heater installation calls for the use of ½” gas line, Rinnai has two words for you… no problem. Pick the gas line – and the Rinnai – that’s right for you.‡

Rinnai Tankless Water Heaters are designed to always provide maximum performance and operating efficiency using either a ¾” or ½” gas line, as long as sufficient gas flow is available.

Because an undersized gas line can stress a tankless system and potentially reduce its life span, Rinnai Tankless Water Heaters, unlike other tankless water heaters, are equipped with innovative technology that safely ceases operation if it detects inadequate gas flow in order to avoid compromising performance and efficiency.

The table to the left lists the maximum length for both ½” and ¾” gas lines when paired with each of Rinnai’s Tankless Water Heaters.

How To Properly Size Your Gas Line:

  • Determine what type of gas is being utilized
  • Determine the inlet pressure
  • Determine the allowed pressure drop
  • Determine what other types of gas appliances are sharing the gas line
  • Determine the maximum loads expected on the whole system as stated in the National Fuel Gas Code

Source: NFPA 54/ANSI Z223.1 National Fuel Gas Code.

‡For complete information on gas sizing for Rinnai Tankless Water Heaters, consult the Operation and Installation Manual.

Optimized Concentric Venting for Non-Condensing Tankless Water Heaters

Rinnai Tankless Water Heaters were the first to use a unique Concentric Venting System, a single-vent assembly option featuring an inner tube for exhaust and an outer tube for fresh air from outdoors. The result is a direct-vent, sealed combustion system that offers optimum safety and performance.

Beyond performance, our concentric system option can make installation faster and easier with:

  • Single penetration through the wall reducing install time and costs
  • Simple positive-fit components for secure connection
  • Joint seals that expand and contract with weather to prevent damage
  • Ease of assembly, adjustment and disassembly

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To further enhance the performance of Rinnai tankless water heating products, these accessories add even more flexibility.

Scale Cutter System





Grundfos Pump with Timer Kit

Condensate Neutralizer Kit

Pipe Cover Enclosure

Recess Box